Labour's Mt Roskill candidate Michael Wood involved in bust up

Labour's Mt Roskill candidate Michael Wood has been involved in a bust up with the partner of his National Party rival following a heated by-election debate on Wednesday night.

It's claimed Mr Wood took exception to comments about his wife, Julie Fairey, from National Party supporters seated in the front row, which included National candidate Parmjeet Parmar's husband.

Ms Fairey is the chairwoman of the Puketapapa local board for the Auckland Council.

The debate was hosted by local newspaper Central Leader and was a raucous affair with the public loudly interjecting during most answers.

Mr Wood took offence to one particular comment during the debate, which saw him lose his patience and allegedly threaten the man who made it while he was still on stage. That man happens to be his opponent's husband, Ravinder Parmar.

"Excuse me, if I hear comments about my wife from the National Party front row, there might be some problems after this meeting," Mr Wood is heard saying in a video from the event.

It came after Parmjeet referred to the Labour candidate as a "yes man" because of his and his wife's ties to Auckland Council.

Once the debate was over, Mr Wood allegedly delivered his promise - confronting Ravinder, as witnessed by National Party member Graham Collins.

"He was manhandling Mr Parmar, threatening him," Mr Collins says. "He had his arms around Mr Parmar, physically. He definitely had him in some sort of hold," says Mr Collins.

"I moved to separate them as they were being manhandled. I put my hands on Mr Wood's shoulders to keep him away to calm him down," he says.